Communication device and feeder device

ABSTRACT

A communication device includes a sensor, an antenna, and a notification component. The sensor is configured to detect magnetic field strength. The antenna is configured to generate a magnetic field. The antenna is further configured to communicate with a wireless device that is configured to generate a magnetic field during communication. The notification component is configured to notify a positional offset between the antenna and the wireless device based on output signal indicative of the magnetic field strength. The sensor is arranged with respect to the antenna such that an effect of the magnetic field generated by the antenna on the output signal is suppressed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application Nos.2013-041508 filed on Mar. 4, 2013 and 2013-127809 filed on Jul. 18,2013. The entire disclosures of Japanese Patent Application Nos.2013-041508 and 2013-127809 are hereby incorporated herein by reference.

BACKGROUND

1. Field of the Invention

This invention generally relates to a communication device and a feederdevice.

2. Background Information

Generally, an RFID (radio frequency identification) has been used tosend and receive information by short-range wireless communication.

RFID tags are used for the RFID (hereinafter, an “RFID tag” will also bereferred to as an “RF tag” or a “wireless device”). RFID tags haveindividual identification information in an internal memory, and performcommunication with an RFID reader that makes use of radio waves orelectromagnetism (hereinafter, an “RFID reader” will also be referred toas an “RF reader” or a “communication device”).

RFID is used in a variety of fields, such as stock control and securitymanagement. Particularly in recent years, merchandise and serviceinformation, and URL information about merchandise and services, storedon RF tags are displayed a tablet terminal by communicating with the RFtag and the tablet terminal, which serves as an RF reader. When a tabletterminal acquires URL information, the web page at that URL can beopened with a browser, either automatically or after user authorization.

Large tablet terminals have debuted in recent years. The antenna used tocommunicate with the RF tag is usually disposed in an area on the rearface side, inside the tablet terminal. Therefore, in communication withan RF tag, the rear face of the tablet terminal is moved closer to theRF tag. However, it is difficult for the user to grasp the relationbetween the RF tag and the antenna on the rear face of the tabletterminal. This results in positional offset. Particularly if the tabletterminal is larger in size, there tends to be a great deal of positionaloffset between the antenna and the RF tag.

Patent Literature 1 (Japanese Unexamined Patent Application PublicationNo. 2010-130729) discloses a charging device that performs charging byreceiving electrical power from a transmission device. The chargingdevice includes four magnetic sensors. The coil magnetic flux (ormagnetic force) generated from the transmission device is detected bythese magnetic sensors, thereby determining the positional relationbetween the transmission device and the charging device. The user can beprompted to set the positional relation between the transmission deviceand the charging device to a positional relation that is suited tocharging. Specifically, an arrow is displayed on the display componentof the charging device based on the positional relation determined.

SUMMARY

An antenna of an RF reader generates a magnetic field when current flowsto the antenna. This magnetic field is detected by the magnetic sensorsof the RF reader. That is, the magnetic sensors detect both the magneticfield generated from the RF tag and the magnetic field generated fromthe RF reader. This makes it difficult to determine accurately theposition of the RF tag based on the detection result.

Even with a system that sends electrical power from a feeder device to areceiver device in a non-contact fashion (i.e., without requiring anyphysical or electrical connection), the magnetic sensors of the feederdevice detect both the magnetic field that is generated from the feederelement of the feeder device, and the magnetic field that is generatedfrom the receiver element of the receiver device based on the magneticfield generated from the feeder element. Therefore, it is difficult forthe feeder device to determine accurately the position of the receiverdevice.

One aspect is to provide a communication device with which a position ofa wireless device can be detected at high accuracy. Another aspect is toprovide a feeder device with which a position of a receiver element of areceiver device.

In view of the state of the known technology, a communication deviceincludes a sensor, an antenna, and a notification component. The sensoris configured to detect magnetic field strength. The antenna isconfigured to generate a magnetic field. The antenna is furtherconfigured to communicate with a wireless device that is configured togenerate a magnetic field during communication. The notificationcomponent is configured to notify a positional offset between theantenna and the wireless device based on output signal indicative of themagnetic field strength. The sensor is arranged with respect to theantenna such that an effect of the magnetic field generated by theantenna on the output signal is suppressed.

Furthermore, in view of the state of the known technology, a feederdevice includes a sensor, a feeder element, and a notificationcomponent. The sensor is configured to detect magnetic field strength.The feeder element is configured to generate a magnetic field. Thefeeder element is further configured to perform a non-contact electricalpower transmission to a receiver element of a receiver device. Thenotification component is configured to notify a positional offsetbetween the antenna and the receiver element based on output signalindicative of the magnetic field strength. The sensor is arranged withrespect to the feeder element such that an effect of the magnetic fieldgenerated by the feeder element on the output signal is suppressed.

Also other objects, features, aspects and advantages of the presentdisclosure will become apparent to those skilled in the art from thefollowing detailed description, which, taken in conjunction with theannexed drawings, discloses one embodiment of the communication deviceand the feeder device.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a schematic diagram of an RFID system in accordance with afirst embodiment;

FIG. 2 is a block diagram of an RF tag (e.g., a wireless device) of theRFID system illustrated in FIG. 1;

FIG. 3 is a block diagram of an RF reader (e.g., a communication device)of the RFID system illustrated in FIG. 1;

FIG. 4 is a plan view of the RF tag and the RF reader, illustrating thatthe RF tag and the RF reader are in a state of positional offset;

FIG. 5 is a perspective view of the RF tag and the RF reader,illustrating that the RF tag and the RF reader are in a state ofpositional offset;

FIG. 6 is a plan view of a first example of the internal configurationof the RF reader;

FIG. 7 is a cross sectional view of the RF reader, taken along VII-VIIline in FIG. 6;

FIG. 8 is a flowchart of a processing executed by a controller of the RFreader;

FIG. 9 is a plan view of a first layout example of magnetic sensors;

FIG. 10 is a plan view of a second layout example of magnetic sensors;

FIG. 11 is a plan view of a third layout example of magnetic sensors;

FIG. 12 is a schematic diagram of a first display example on a displaycomponent of the RF reader;

FIG. 13 is a schematic diagram of a second display example on thedisplay component;

FIG. 14 is a schematic diagram of a third display example on the displaycomponent;

FIG. 15 is a schematic diagram of a fourth display example on thedisplay component;

FIG. 16 is a plan view of a second example of the internal configurationof an RF reader in accordance with a second embodiment;

FIG. 17 is a cross sectional view of the RF reader, taken alongXVII-XVII line in FIG. 16;

FIG. 18 is a plan view of a third example of the internal configurationof an RF reader in accordance with a second embodiment;

FIG. 19 is a cross sectional view of the RF reader, taken along XIX-XIXline in FIG. 18;

FIG. 20 is a plan view of a modification example of an RF reader;

FIG. 21 is a plan view of a first modification example of an antennacoil;

FIG. 22 is a cross sectional view of the RF reader, taken alongXXII-XXII line in FIG. 21;

FIG. 23 is a plan view of a second modification example of an antennacoil;

FIG. 24 is a plan view of a third modification example of an antennacoil;

FIG. 25 is a plan view of a fourth modification example of an antennacoil;

FIG. 26 is a schematic diagram of a first example of a non-contact powerfeed system in accordance with a third embodiment;

FIG. 27 is a block diagram of the configurations of a receiver deviceand a feeder device of the non-contact power feed system;

FIG. 28 is a plan view of the receiver device and the feeder device,illustrating that a receiver element of the receiver device and a feederelement of the feeder device are in a state of positional offset;

FIG. 29 is a perspective view of the receiver element and the feederelement, illustrating that the receiver element and the feeder elementare in a state of positional offset;

FIG. 30 is a plan view of a first example of the internal configurationof the feeder device;

FIG. 31 is a cross sectional view of the feeder device, taken alongXXXI-XXXI line in FIG. 30;

FIG. 32 is a flowchart of a processing executed by a controller of thefeeder device;

FIG. 33 is a plan view of a fourth layout example of magnetic sensors;

FIG. 34 is a plan view of a fifth layout example of magnetic sensors;

FIG. 35 is a plan view of a sixth layout example of magnetic sensors;

FIG. 36 is a schematic diagram of a fifth display example on a displaycomponent of the feeder device;

FIG. 37 is a schematic diagram of a sixth display example on the displaycomponent;

FIG. 38 is a schematic diagram of a seventh display example on thedisplay component;

FIG. 39 is a schematic diagram of an eighth display example on thedisplay component;

FIG. 40 is a plan view of a second example of the internal configurationof a feeder device in accordance with a fourth embodiment;

FIG. 41 is a cross sectional view of the feeder device, taken alongXLI-XLI line in FIG. 40;

FIG. 42 is a plan view of a third example of the internal configurationof a feeder device in accordance with a fourth embodiment;

FIG. 43 is a cross sectional view of the feeder device, taken alongXLIII-XLIII line in FIG. 42;

FIG. 44 is a plan view of a modification example of a feeder element ofthe feeder device;

FIG. 45 is a plan view of a fifth modification example of an antennacoil;

FIG. 46 is a cross sectional view of the feeder device, taken alongXLVI-XLVI line in FIG. 45;

FIG. 47 is a plan view of a sixth modification example of an antennacoil;

FIG. 48 is a plan view of a seventh modification example of an antennacoil;

FIG. 49 is a plan view of an eighth modification example of an antennacoil; and

FIG. 50 is a schematic diagram of a second example of a non-contactpower feed system.

DETAILED DESCRIPTION OF EMBODIMENTS

Selected embodiments will now be explained with reference to thedrawings. It will be apparent to those skilled in the art from thisdisclosure that the following descriptions of the embodiments areprovided for illustration only and not for the purpose of limiting theinvention as defined by the appended claims and their equivalents.

First Embodiment

Referring initially to FIGS. 1 to 15, an RFID system is illustrated thatis equipped with an RF tag 1 and an RF reader 2 in accordance with afirst embodiment. In the illustrated embodiment, while the RF tag 1 andthe RF reader 2 are illustrated as examples of the wireless device andthe communication device of the present invention, it will be apparentto those skilled in the art from this disclosure that the presentinvention can be applied to different types of wireless devices andcommunication devices.

FIG. 1 is a simplified diagram of an example of an RFID system. FIG. 2is a diagram of an example of the configuration of the RF tag 1 (e.g.,the wireless device). FIG. 3 is a diagram of an example of theconfiguration of the RF reader 2 (e.g., the communication device).

The RF tag 1 is attached to a poster 100 or the like as shown in FIG. 1,for example. The user can acquire information from the RF tag 1 bymoving an antenna coil 21 (discussed below) of the RF reader 2 close tothe RF tag 1. In FIG. 1, the antenna coil 21 is disposed in an area inthe lower middle part of the rear face of the RF reader 2. However,there are no particular restrictions about where on the RF reader 2 theantenna coil 21 is disposed.

Referring now to FIG. 2, the RF tag 1 will now be described. The RF tag1 in this embodiment is a passive tag. A passive tag is a tag thatoperates by non-contact power transmission from the RF reader 2. Thepassive tag has no built-in battery or other such power supply. The RFtag 1 can instead be an active tag, however. An active tag is a tag thathas an internal power supply. The active tag emits radio waves under itsown power during communication. Thus, the communication distance islonger than with a passive tag.

As shown in FIG. 2, the RF tag 1 includes an antenna coil 11 (e.g., anantenna), a communication component 12, a memory component 13, and acontroller 14. Transmission of data signals and drive energy byelectromagnetic induction can be accomplished with an RFID system bymoving the antenna coil 21 of the RF reader 2 (discussed below) close tothe antenna coil 11 so that they are electromagnetically coupled. Whencurrent flows to the antenna coil 11, a magnetic field is generated,which affects the antenna coil 21 of the RF reader 2. A commonly usedfrequency for the electromagnetic waves, such as 13.56 MHz, can be used,or some other frequency can be used instead. The communicable distancebetween the antenna coil 11 and the antenna coil 21 of the RF reader 2is preset to a range of about a few centimeters to a few dozencentimeters, for example.

The communication component 12 outputs to the antenna coil 11 atransmission signal obtained by subjecting the data sent to the RFreader 2 to specific encoding and modulation. The antenna coil 11 thathas acquired a transmission signal sends the data to the RF reader 2 byelectromagnetic induction.

The memory component 13 is a memory means for storing various kinds ofinformation. An EEPROM is used, for example. The memory component 13stores an identification number for the RF tag 1, information to betransmitted to the RF reader 2, and other such information.

The controller 14 is a control means or processor for controlling theentire RF tag 1. The controller 14 sends the data stored in the memorycomponent 13 through the communication component 12 and the antenna coil11 to the RF reader 2, according to a read request received from the RFreader 2.

Referring now to FIG. 3, the RF reader 2 will now be described. The RFreader 2 includes the antenna coil 21 (e.g., an antenna), acommunication component 22, a detector 23, a magnetic sensor 24, adisplay component 25, and a controller 26.

The antenna coil 21 includes a loop antenna that is wound in a flat,annular spiral on a substrate (not shown). The two ends of the antennacoil 21 are connected to the communication component 22 of the RF reader2 via terminals (not shown). When current flows to the antenna coil 21,a magnetic field is generated at the antenna coil 21. As discussedabove, the transmission of data signals and drive energy can beaccomplished by moving the antenna coil 21 close to the antenna coil 11of the RF tag 1 such that it is electromagnetically coupled with theantenna coil 11 of the RF tag 1.

The communication component 22 acquires data inputted from the antennacoil 11 of the RF tag 1 to the antenna coil 21. The communicationcomponent 22 reads data obtained by subjecting the acquired data tospecific demodulation and decoding.

The detector 23 inputs to the controller 26 the output signal (ordetection result) of the magnetic sensor 24. The magnetic sensor 24detects the strength of the magnetic field generated from the antennacoil 11 of the RF tag 1. The magnetic sensor 24 detects the strength ofthe magnetic field in the superposition direction of the antenna coil 21and the antenna coil 11 of the RF tag 1 (see FIG. 4, discussed below).The magnetic sensor 24 is formed by a pickup coil, a magnetic resistanceelement (MR element), a Hall element, a magnetic impedance element (MIelement), or the like. In this embodiment, the RF reader 2 includes oneor more magnetic sensors 24. The layout of the magnetic sensor 24 willbe discussed in detail below.

The display component 25 displays a specific image or video. The displaycomponent 25 in this embodiment also serves as an interface unit havinga touch panel function. However, a separate interface unit with orwithout a touch panel function can be used instead. Informationindicating the direction of the RF tag 1 is displayed on the displaycomponent 25, as discussed below.

The controller 26 is a control means or processor for controlling theentire RF reader 2. The controller 26 includes a CPU 261, a ROM 262, anda RAM 263. Programs to be executed by the controller 26. Parameters anddata necessary for the execution of these programs are stored in the ROM262. The CPU 261 executes various kinds of program stored in the ROM262. The RAM 263 temporarily stores data obtained as a result of variouskinds of processing, and data obtained in the course of various kinds ofprocessing. The CPU 261, ROM 262, RAM 263, etc., are connected via abus. Some or all of the CPU 261, ROM 262, and RAM 263 can be integratedinto a single chip.

The controller 26 determines the position and/or direction of the RF tag1 based on the output signal of the magnetic sensor 24 inputted from thedetector 23. The controller 26 displays information indicating theposition and/or direction of the RF tag 1 on the display component 25.How the position of the RF tag 1 is determined and its display on thedisplay component 25 will be discussed in detail below.

Next, the layout of the magnetic sensor 24 in the RF reader 2 will bedescribed through reference to FIGS. 4 and 5. FIG. 4 is a plan view ofwhen the RF tag 1 and the RF reader 2 are in a state of positionaloffset. FIG. 5 is an oblique view of when the RF tag 1 and the RF reader2 are in a state of positional offset. FIG. 6 is a plan view of anexample of the internal configuration of the RF reader 2. FIG. 7 is alateral cross section along the VII-VII line in FIG. 6.

As discussed above, the communicable distance between the antenna coil11 and the antenna coil 21 is set to between about a few centimeters anda few dozen centimeters. In particular, when the communicable distanceis set to a few centimeters, the RF reader 2 can not read theinformation of the RF tag 1 if the positional offset between the antennacoil 11 and the antenna coil 21 is large when the RF reader 2 is movedtoward the RF tag 1.

This “positional offset” between the antenna coil 11 and the antennacoil 21 refers to a state in which the antenna coil 11 is not presentwithin the region of the antenna coil 21 (i.e., the region indicated bythe hatching lines in FIG. 4) when projected in the superpositiondirection of the antenna coil 11 and the antenna coil 21 (i.e., thedirection perpendicular to the paper plane in FIG. 4) while the RFreader 2 is moved toward the RF tag 1, as shown in FIG. 4. Moreprecisely, as shown in FIG. 5, this phrase refers to a state in whichthe distance between the center axis of the antenna coil 21 and thecenter axis of the antenna coil 11 is at least a specific distance L. Inthe illustrated embodiment, the specific distance L can be thecommunicable distance, or it can be any distance that is less than thecommunicable distance.

As shown in FIGS. 4 and 5, if the positional offset has occurred, thenthere can be communication problems, depending on the communicabledistance between the antenna coil 11 and the antenna coil 21. Therefore,in this embodiment, the controller 26 determines the position and/ordirection of the RF tag 1 based on the output signal of the magneticsensor 24 that is inputted from the detector 23. Then, the controller 26displays information indicating the position and/or direction of the RFtag 1 on the display component 25.

As discussed above, the magnetic sensor 24 detects the strength of themagnetic field generated from the antenna coil 11. However, the magneticsensor 24 also detects the strength of the magnetic field generated fromthe antenna coil 21. The strength of the magnetic field generated fromthe antenna coil 11 is weaker than the strength of the magnetic fieldgenerated from the antenna coil 21, particularly when the RF tag 1 is apassive tag. Thus, it is conceivable that the magnetic sensor 24 willdetect mainly the strength of the magnetic field generated from theantenna coil 21.

In view of this, the magnetic sensor 24 is disposed at a position whereit is less likely that a signal indicating the strength of the magneticfield generated from the antenna coil 21 will be included in the outputsignal of the magnetic sensor 24. In this embodiment, as shown in FIG.6, the magnetic sensor 24 only includes two magnetic sensors 24 a and 24b (e.g., two magnetic sensor elements). These magnetic sensors 24 a and24 b are made of magnetic resistance elements.

As shown in FIG. 7, the magnetic field generated from the antenna coil21 has a first region R1 and a second region R2 with mutually oppositeorientations or directions of the magnetic flux. The magnetic sensors 24a and 24 b are respectively disposed at positions that allow thedetections of the strength of the magnetic field in part of the firstregion and the strength of the magnetic field in part of the secondregion, out of the magnetic field generated from the antenna coil 21.This will now be described in detail through reference to FIGS. 6 and 7.In the following description, the fact that the magnetic sensors 24 aand 24 b detect the strength of the magnetic field in part of the firstregion and in part of the second region, respectively, will also bestated simply as “detects the strength of the magnetic field in thefirst region and the second region.” In the illustrated embodiment, asshown in FIG. 7, the first region R1 is located outside the antenna coil21, while the second region R2 is located inside the antenna coil 21.

As shown in FIG. 6, the magnetic sensors 24 a and 24 b are respectivelydisposed at a position where the strength of the magnetic field in partof the first region outside of the antenna coil 21 is detected, and aposition where the strength of the magnetic field in part of the secondregion inside of the antenna coil 21 is detected. The detector 23obtains a magnetic field strength by adding the strength of the magneticfield of the antenna coil 21 detected by the magnetic sensor 24 a to thestrength of the magnetic field of the antenna coil 21 detected by themagnetic sensor 24 b. The detector 23 outputs the magnetic fieldstrength to the controller 26 as the strength of the magnetic field ofthe antenna coil 21 detected by the magnetic sensor 24.

As shown in FIG. 7, in the illustrated embodiment, the magnetic sensors24 a and 24 b are disposed in the first region and the second region,respectively, with the antenna coil 21 in between. Thus, the orientationof the magnetic flux detected by the magnetic sensor 24 a issubstantially the opposite of the orientation of the magnetic fluxdetected by the magnetic sensor 24 b. Therefore, if the absolute valuesof the strength of the magnetic field of the antenna coil 21 detected bythe magnetic sensors 24 a and 24 b are substantially the same, then thestrength of the magnetic field of the antenna coil 21 detected by themagnetic sensor 24 as calculated by adding together the two outputsignals of the magnetic sensors 24 a and 24 b becomes substantiallyzero. Thus, it will be less likely that a signal indicating the strengthof the magnetic field of the antenna coil 21 is included in the outputsignal of the magnetic sensor 24. Accordingly, the magnetic sensor 24will function mainly as a sensor for detecting the strength of themagnetic field of the antenna coil 11 while the antenna coil 11 and theantenna coil 21 are moved close together. In other words, in the outputsignals of the magnetic sensors 24 a and 24 b, the signal componentsindicative of the strength of the magnetic field of the antenna coil 21are cancelled out with respect to each other, while the signalcomponents indicative of the strength of the magnetic field of theantenna coil 11 can be solely detected.

The processing executed by the controller 26 of the RF reader 2 will nowbe described. FIG. 8 is a flowchart of an example of the processingexecuted by the controller 26 of the RF reader 2 in this embodiment.

The controller 26 starts the processing for performing a display thatindicates the position and/or direction of the RF tag 1 whencommunication commences between the antenna coil 11 and the antenna coil21. In step S01, the controller 26 acquires the output signal of themagnetic sensor 24 from the detector 23. As discussed above, it is lesslikely that a signal indicating the strength of the magnetic field ofthe antenna coil 21 is included in the output signal of the magneticsensor 24. Thus, the output signal of the magnetic sensor 24 mainlyincludes a signal indicating the strength of the magnetic field of theantenna coil 11.

In step S02, the controller 26 determines the positional relationbetween the antenna coil 11 and the antenna coil 21. As shown in FIG. 6,in the illustrated embodiment, the RF reader 2 includes a singlemagnetic sensor 24 (i.e., a single pair of the magnetic sensors 24 a and24 b). In this case, the output signal of the magnetic sensor 24 iscompared to a specific threshold to determine how near or far theantenna coil 21 is to or from the antenna coil 11.

On the other hand, as shown in FIG. 9, if the RF reader 2 includes twomagnetic sensors 24 (e.g., magnetic sensors 241 and 242), then theoutput signals of one magnetic sensor 24 (e.g., the magnetic sensor 241)and the other magnetic sensor 24 (e.g., the magnetic sensor 242) arecompared to determine the one-dimensional direction of the antenna coil11. Specifically, in this embodiment, the antenna coil 21 is disposed inan area in the lower middle part of the RF reader 2. Thus, there israrely positional offset in the up and down direction (the Y directionin FIG. 4), while there is often positional offset in the left and rightdirection (the X direction in FIG. 4). In view of this, as shown in FIG.9, the magnetic sensors 24 are disposed on two sides of the antenna coil21 extending in the up and down direction.

With this configuration, if the strength of the magnetic field is higherwith the output signal of the magnetic sensor 242 than with the outputsignal of the magnetic sensor 241, for example, then it is determinedthat the antenna coil 11 of the RF tag 1 is present in the directiontowards the magnetic sensor 242 with respect to the center point O ofthe antenna coil 21 as the center. The layout of the two magneticsensors 24 can be varied according to the position of the antenna coil21 in the RF reader 2. For example, when the antenna coil 21 is disposedin an area in the left middle part of the RF reader 2, it is believedthat positional offset will frequently occur in the up and downdirection. In view of this, the magnetic sensors 24 can be disposed ontwo sides of the antenna coil 21 extending in the left and rightdirection.

Furthermore, as shown in FIG. 10, if the RF reader 2 includes threemagnetic sensors 24 (e.g., magnetic sensors 243, 244, and 245), or morethan three magnetic sensors 24, then the two-dimensional directions ofthe antenna coil 11 are determined by comparing the output signals ofthe magnetic sensors 24.

As shown in FIG. 10, in the illustrated embodiment, a total of threemagnetic sensors 24 are disposed on two sides (two straight parts) ofthe antenna coil 21 extending in the left and right direction. Onemagnetic sensor 24 (e.g., the magnetic sensor 243) is disposed on oneside, while two magnetic sensors 24 (e.g., the magnetic sensors 244 and245) is disposed on the other side. Positional offset in the up and downdirection with respect to the RF tag 1 is determined by comparing theoutput signal of the magnetic sensor 243 with the output signal of themagnetic sensors 244 and/or 245. Also, positional offset of the antennacoil 21 in the left and right direction with respect to the antenna coil11 is determined by comparing the output signals of the magnetic sensor244 and the magnetic sensor 245.

The controller 26 determines positional offset in two-dimensionaldirections based on the positional offset in the up and down directionand in the left and right direction thus determined. There are noparticular restrictions on the number of magnetic sensors 24. However,the position and/or direction of the RF tag 1 can be determined moreaccurately by disposing more magnetic sensors 24. For example, as shownin FIG. 11, the positional offset in the up and down direction or in theleft and right direction with respect to the RF tag 1 can be determinedfor each side by disposing two magnetic sensors 24 on each side of theantenna coil 21.

In step S03, the controller 26 displays the position and/or direction ofthe antenna coil 11 on the display component 25 based on the positionalrelation between the antenna coil 11 and the antenna coil 21 determinedin step S02. For example, if the layout of the magnetic sensor 24 is asshown in FIG. 6, then a display indicating how near or far the antennacoil 21 is to or from the antenna coil 11 is given as shown in FIG. 12.If the layout of the magnetic sensors 24 is as shown in FIG. 9, then adisplay indicating the one-dimensional direction of the antenna coil 11with respect to the center point O of the antenna coil 21 as a referenceis given as shown in FIG. 13. If the layout of the magnetic sensors 24is as shown in FIGS. 10 and 11, then a display indicating thetwo-dimensional directions of the antenna coil 11 with respect to thecenter point O of the antenna coil 21 as a reference is given as shownin FIG. 14.

In the layout of the magnetic sensor 24 shown in FIG. 6, when thedifference between the output signal of the magnetic sensor 24 and thespecific threshold is at or below a specific value, no positional offsethas occurred between the antenna coil 11 and the antenna coil 21, or ifit has occurred, it is so minor that it can be ignored. Also, when thedifference between the output signals of the magnetic sensors 24 in thelayout of the magnetic sensors 24 shown in FIGS. 9 to 11 is at or belowa specific value, no positional offset has occurred between the antennacoil 11 and the antenna coil 21, or if it has occurred, it is so minorthat it can be ignored. In this case, the controller 26 does not need todisplay anything on the display component 25, or can give a displayindicating that no positional offset has occurred, as shown in FIG. 15,for example.

In step S04, the controller 26 determines whether or not communicationhas ended between the antenna coil 11 and the antenna coil 21. Ifcommunication has not ended (No in step S04), then the flow returns tostep S01. With this configuration, if the RF reader 2 is moved, then thedisplay indicating the position and/or direction of the antenna coil 11is updated. If communication has ended (Yes in step S04), then theprocessing is concluded.

Alternatively or additionally, when communication between the antennacoil 11 and the antenna coil 21 has not yet ended, it can be determinedin step S03 whether or not a specific length of time has elapsed sincethe display indicating the position and/or direction of the antenna coil11 was given. If this length of time has elapsed, then the flow returnsto step S01. With this configuration, the display is refreshed atregular time intervals.

In the illustrated embodiment, the RF reader (e.g., the communicationdevice) includes the magnetic sensor (e.g., the sensor), the antennacoil (e.g., the sensor), and the controller (e.g., the notificationcomponent or notification means). The magnetic sensor detects thestrength of the magnetic field (e.g., the magnetic field strength). Theantenna coil generates a magnetic field. The antenna coil communicateswith the RF tag (e.g., the wireless device) that generates a magneticfield during communication. The controller makes a notification relatedto positional offset between the antenna coil and the RF tag based onoutput signal from the magnetic sensor. In other words, the controllernotifies a positional offset between the antenna coil and the RF tagbased on the output signal indicative of the magnetic field strength.

The magnetic sensor is disposed at a position where it is less likelythat a signal indicating the strength of the magnetic field generatedfrom the antenna coil of the RF reader when current flows to the antennacoil of the RF reader will be included in the output signal of themagnetic sensor. In other words, the magnetic sensor is arranged withrespect to the antenna coil such that an effect of the magnetic fieldgenerated by the antenna coil on the output signal is suppressed.

Thus, the output signal of the magnetic sensor mainly includes a signalindicating the strength of the magnetic field generated from the RF tagthat communicates with the RF reader. Therefore, the position and/ordirection of the RF tag can be accurately detected based on the outputsignal of the magnetic sensor. Also, the notification can be givenrelated to the positional offset between the antenna coil of the RF tagand the antenna coil of the RF reader.

In the illustrated embodiment, the magnetic field generated from theantenna coil has a first region and a second region with mutuallyopposite orientations of the magnetic flux. The magnetic sensor isdisposed at a position where the strength of the magnetic field of thefirst region and the strength of the magnetic field of the second regioncan be detected. In other words, the magnetic sensor is arranged withrespect to the antenna coil such that the magnetic sensor is configuredto detect the magnetic field strength in first and second regions,respectively. The magnetic field generated by the antenna has mutuallyopposite magnetic flux orientations in the first and second regions,respectively.

In the illustrated embodiment, the detected strength of the magneticfield of the first region and the strength of the magnetic field of thesecond region are added together. This makes it less likely that asignal indicating the strength of the magnetic field generated from theantenna coil of the RF reader will be included in the output signal ofthe magnetic sensor. In other words, the magnetic sensor is arrangedwith respect to the antenna coil such that the magnetic field strengthdetected in the first and second regions cancels out with respect toeach other. Thus, the position and/or direction of the RF tag can bedetected more accurately.

In the illustrated embodiment, the controller calculates the one- ortwo-dimensional positional offset direction of the antenna coil of theRF tag with respect to the antenna coil of the RF reader based on theoutput signal of the magnetic sensor, and gives the notification of thedirection of the RF tag. In other words, the controller calculates apositional offset direction of the RF tag with respect to the antennacoil of the RF reader based on the output signal. The controllernotifies the positional offset direction of the RF tag. Thus, the usercan communicate more stably with the RF tag by moving the RF readerbased on this notification.

In the illustrated embodiment, the controller gives a notificationindicating that there is no positional offset when the positional offsetbetween the antenna coil of the RF tag and the antenna coil of the RFreader is below a specific threshold based on the output signal of themagnetic sensor. In other words, the controller notifies that there isno positional offset while the positional offset between the RF tag andthe antenna coil of the RF reader is below a specific threshold based onthe output signal. Thus, the user can communicate more stably with theRF tag by maintaining the current position of the RF reader.

Second Embodiment

Referring now to FIGS. 16 to 25, an RFID system in accordance with asecond embodiment will now be explained. In view of the similaritybetween the first and second embodiments, the parts of the secondembodiment that are functionally identical to the parts of the firstembodiment will be given the same reference numerals as the parts of thefirst embodiment. Moreover, the descriptions of the parts of the secondembodiment that are identical to the parts of the first embodiment maybe omitted for the sake of brevity.

In the first embodiment, a magnetic resistance element is used as themagnetic sensor 24. In the second embodiment, a less expensive pickupcoil is used as the magnetic sensor 24. This pickup coil include acircular pickup coil (or loop coil), and a figure-eight pickup coil.

FIG. 16 is a plan view of a second example of the internal configurationof the RF reader 2. FIG. 17 is a lateral cross section along XVII-XVIIline in FIG. 16. FIG. 18 is a plan view of a third example of theinternal configuration of the RF reader 2. FIG. 19 is a lateral crosssection along XIX-XIX line in FIG. 18. In the illustrated embodiment, asshown in FIGS. 16 and 17, the RF reader 2 includes a circular pickupcoil as the magnetic sensor 24. Alternatively, as shown in FIGS. 18 and19, the RF reader 2 can include a figure-eight pickup coil as themagnetic sensor 24. The magnetic sensor 24 is also called the pickupcoil 24 below.

As shown in FIGS. 16 and 17, as viewed in a direction perpendicular tothe paper plane in FIG. 16, the magnetic field generated from theantenna coil 21 is separated into a magnetic field generated in thefirst region outside of the antenna coil 21 (e.g., a first magneticfield) and a magnetic field generated in the second region inside of theantenna coil 21 (e.g., a second magnetic field). The orientations of themagnetic flux of these magnetic fields are mutually opposite, as shownin FIG. 17. The circular pickup coil 24 includes first and second sensorcomponents 246 and 247. The first sensor component 246 detects thestrength of the magnetic field of part of the first region, while thesecond sensor component 247 detects the strength of the magnetic fieldof part of the second region. The detector 23 obtains the strength ofthe magnetic field by adding together the strength of the magnetic fieldof the antenna coil 21 detected by the first sensor component 246 andthe strength of the magnetic field of the antenna coil 21 detected bythe second sensor component 247. The detector 23 further outputs theobtained strength of the magnetic field to the controller 26 as thestrength of the magnetic field of the antenna coil 21 detected by thepickup coil 24.

As shown in FIG. 16, the first sensor component 246 and the secondsensor component 247 are respectively disposed so as to detect thestrength of the magnetic field of part of the first region and part ofthe second region, respectively. Furthermore, as shown in FIG. 17, theorientation of the magnetic flux detected by the first sensor component246 and the orientation of the magnetic flux detected by the secondsensor component 247 are substantially opposite directions. Therefore,if the absolute values of the strength of the magnetic field of theantenna coil 21 detected by the first sensor component 246 and thesecond sensor component 247 are substantially the same, then thestrength of the magnetic field of the antenna coil 21 detected by thepickup coil 24 as calculated by adding together the two output signalswill be substantially zero. That is, it will be less likely that asignal indicating the strength of the magnetic field of the antenna coil21 will be included in the output signal of the pickup coil 24. Thus,the pickup coil 24 will function mainly as a sensor for detecting thestrength of the magnetic field of the antenna coil 11 when the antennacoil 11 and the antenna coil 21 are moved close together.

Similarly, as shown in FIGS. 18 and 19, the figure-eight-shaped pickupcoil 24 includes a first coil 248 and a second coil 249. The first coil248 and the second coil 249 are respectively disposed at a positionwhere the strength of part of the magnetic field outside of the antennacoil 21 (e.g., the first region) is detected, and a position where thestrength of part of the magnetic field inside of the antenna coil 21(e.g., the second region) is detected. The detector 23 obtains thestrength of the magnetic field by adding together the strength of themagnetic field of the antenna coil 21 detected by the first coil 248 andthe strength of the magnetic field of the antenna coil 21 detected bythe second coil 249. The detector 23 outputs the strength of themagnetic field to the controller 26 as the strength of the magneticfield of the antenna coil 21 detected by the pickup coil 24.

As shown in FIG. 19, the first coil 248 and the second coil 249 aredisposed so as to detect the strength of the magnetic field in the firstregion and the second region, respectively. The orientation of themagnetic flux detected by the first coil 248 and the orientation of themagnetic flux detected by the second coil 249 are substantially oppositedirections. Therefore, if the absolute values of the strength of themagnetic field of the antenna coil 21 detected by the first coil 248 andthe second coil 249 are substantially the same, then the strength of themagnetic field of the antenna coil 21 detected by the pickup coil 24 ascalculated by adding together the two output signals will besubstantially zero. That is, it will be less likely that a signalindicating the strength of the magnetic field of the antenna coil 21will be included in the output signal of the pickup coil 24. Thus, thepickup coil 24 will function mainly as a sensor for detecting thestrength of the magnetic field of the antenna coil 11 when the antennacoil 11 and the antenna coil 21 are moved close together.

This embodiment provides the same effect as the first embodiment. Inaddition, an inexpensive pickup coil can be used as the magnetic sensor.Thus, the cost of the RF reader can be decreased.

In the above-mentioned embodiments, the controller 26 gives a display onthe display component 25 indicating the position and/or direction of theantenna coil 11 to notify the user about the position and/or directionof the antenna coil 11. In other words, the controller 26 is an exampleof the notification component (or notification means) of the presentinvention. However, the position and/or direction of the antenna coil 11can instead be conveyed to the user by some method other than a display.For instance, the position and/or direction of the antenna coil 11 canbe conveyed by sound emitted from a speaker. Specifically, as long asthe position and/or direction of the antenna coil 11 can be recognized,any notification method can be employed.

In the above embodiments, when the RF reader 2 includes two magneticsensors 24, the one-dimensional direction of the antenna coil 11 isdetermined. However, two-dimensional directions can be determined whenthe RF reader 2 further has an acceleration sensor that detects themovement direction of the RF reader 2.

This will be described in detail through reference to FIG. 20. FIG. 20is a diagram illustrating a modification example of the RF reader 2. TheRF reader 2 has pickup coils 24 c and 24 d as the magnetic sensors 24.With this configuration, if the strength of the magnetic field of theoutput signal of the pickup coil 24 d is higher than that of the outputsignal of the pickup coil 24 c, then it is determined that the antennacoil 11 is present in the direction towards the pickup coil 24 d (rightdirection) with respect to the center point O of the antenna coil 21 asa reference. In addition, fluctuation in the strength of the magneticfield detected by the pickup coils 24 c and 24 d can also be utilized.For example, if the strength of the magnetic field detected by thepickup coils 24 c and 24 d weakens while the RF reader 2 is moved in thedirection of the arrow D1, then it can be determined that the RF tag 1is present in the upward direction. That is, the antenna coil 11 isdetermined to be present in the right direction and the upward direction(that is, the upper-right direction) from the RF reader 2.

Meanwhile, if the strength of the magnetic field detected by the pickupcoils 24 c and 24 d weakens while the RF reader 2 is moved in thedirection of the arrow D2, then it can be determined that the antennacoil 11 is present in the downward direction. That is, the RF tag 1 isdetermined to be present in the right direction and the downwarddirection (that is, the lower-right direction) from the RF reader 2.

In the above embodiments, the output signal of one magnetic sensor 24 iscompared with a threshold, or the output signals of two or more magneticsensors 24 are compared with respect to each other. Then, theone-dimensional direction or two-dimensional directions of the antennacoil 11 are indicated. However, alternatively, the centroid coordinatesP of the magnetic field generated from the antenna coil 11 can becalculated, and the direction of the centroid coordinates P relative tothe center point O of the antenna coil 21 as a reference can bedetermined as the direction of the antenna coil 11.

When the positional coordinates of an i-th magnetic sensor 24 are(X_(i), Y_(i)), and the output signal of this magnetic sensor 24 is Hi(A/m), then the centroid coordinates P (X, Y) of the magnetic fieldgenerated from the antenna coil 11 satisfy the following equations (1)and (2).

Σ(X _(i) −X)Hi=0  (1)

Σ(Y _(i) −Y)Hi=0  (2)

In the above embodiments, a loop antenna wound in a flat spiral is usedas the antenna coil 21. However, this is not the only option. Forexample, a loop antenna with a three-dimensional spiral shape can beused as shown in FIGS. 21 and 22. In other words, in this example, thespiral shape extends in an axial direction of the antenna coil 21. FIGS.21 and 22 are modification examples of the antenna coil 21 shown inFIGS. 6 and 7, respectively. However, this loop antenna can be appliedto the antenna coil 21 in other embodiments.

Here, the strength of the magnetic field of the antenna coil 21generated in the first region, and the strength of the magnetic field ofthe antenna coil 21 generated in the second region will be furtherdescribed. In the above embodiments, the strength of the magnetic fieldgenerated in the second region of the antenna coil 21 is affected by themagnetic field generated from all parts (the four sides) of the antennacoil 21, while the strength of the magnetic field generated in the firstregion is mainly affected by the magnetic field generated from just onepart (one side) of the antenna coil 21. Therefore, the strength of themagnetic field in the second region is generally higher than thestrength of the magnetic field in the first region.

As shown in FIGS. 23 and 24, when the magnetic sensors 24 are pickupcoils, the sensors that detect the strength of the magnetic field in thesecond region of the magnetic sensors 24 (the second sensor component247 and the second coil 249) can be made smaller than the sensors thatdetect the strength of the magnetic field in the first region (the firstsensor component 246 and the first coil 248). This makes the sum of thestrength of the magnetic field of the antenna coil 21 detected by themagnetic sensor 24 substantially zero.

Also, when the magnetic sensor 24 is a magnetic resistance element asshown in FIGS. 6 and 7, the position at which the magnetic sensor 24 adetects the strength of the magnetic field in the first region can beset closer than the position at which the magnetic sensor 24 b detectsthe strength of the magnetic field in the second region with respect tothe part of the antenna coil 21 that generates the magnetic fielddetected by the magnetic sensors 24 a and 24 b, as shown in FIG. 25.

That is, when the strength of the magnetic field of the first region andthe strength of the magnetic field of the second region are different,the magnetic sensor 24 is disposed such that the detection of thestrength of the magnetic field in the region with the stronger magneticfield will be suppressed more than the detection of the strength of themagnetic field in the region with the weaker magnetic field. In otherwords, the magnetic field generated by the antenna coil has a largerstrength in the second region than in the first region. The magneticsensor is arranged with respect to the antenna coil such that detectionof the magnetic field strength in the second region is suppressed morethan detection of the magnetic field strength in the first region.

Also, alternatively, the strength of the magnetic field of the antennacoil 21 detected by the magnetic sensor 24 can be set to substantiallyzero by adjusting the gain of the output signal of the magnetic field inthe first region and/or the output signal of the magnetic field in thesecond region.

Third Embodiment

Referring now to FIGS. 26 to 39, a non-contact power feed system 300 isillustrated that is equipped with a feeder device 400 and a receiverdevice 500 in accordance with a third embodiment will now be explained.In view of the similarity between the first and second embodiments andthe third embodiment, the parts of the third embodiment that arefunctionally identical to the parts of the first and second embodimentswill be given the same reference numerals or names as the parts of thefirst and second embodiments. Moreover, the descriptions of the parts ofthe third embodiment that are identical to the parts of the first andsecond embodiments may be omitted for the sake of brevity.

In the first and second embodiments above, the user is notified of thedirection of the RF tag 1 when the positional offset occurred betweenthe RF tag 1 and the RF reader 2 in the RFID system. This notificationcan also be applied to when the positional offset has occurred between areceiver element 510 of the receiver device 500 and a feeder element 440of the feeder device 400 in the non-contact power feed system 300.

Referring now to FIGS. 26 and 27, the non-contact power feed system 300will be described in detail. FIG. 26 is a simplified diagram of a firstexample of the non-contact power feed system 300. FIG. 27 is a diagramof the configuration of the non-contact power feed system 300. In thethird and fourth embodiments, the feeder device 400 and the receiverdevice 500 of the non-contact power feed system 300 are illustrated asexamples of the feeder device and the receiver device of the presentinvention in order to give specific embodiments of the technologicalconcept of the present invention. However, the present invention is notlimited to this feeder device and receiver device, and can be equallyapplied to the feeder device and receiver device in other embodimentsencompassed by claims.

As shown in FIG. 26, the non-contact power feed system 300 includes thefeeder device 400 and the receiver device 500. In FIG. 26, the receiverelement 510 is disposed in an area (the lower middle part in FIG. 26) ofthe rear face of the receiver device 500, such as a smart phone or atablet terminal. The user can perform non-contact power feed by movingthe feeder element 440 of the feeder device 400 closer to the receiverelement 510 of the receiver device 500.

As shown in FIG. 26, the receiver device 500 is larger than the feederdevice 400. Thus, to perform the non-contact power feed, the user has tomove the feeder device 400 (i.e., the feeder element 440 of the feederdevice 400) by hand to the position of the receiver element 510 of thereceiver device 500. In view of this, in this embodiment, the user isnotified of the location of the receiver element 510 via a displaycomponent 470 of the feeder device 400.

As shown in FIG. 27, the feeder device 400 includes a power supplycomponent 410, a controller 420, a feed driver 430, a feeder element440, a detector 450, a magnetic sensor 460, and the display component470. The power supply component 410 is supplied with AC power from acommercial power supply (not shown). The power supply component 410supplies power to the controller 420 and the feed driver 430.

The controller 420 is a control means or processor for controlling theentire feeder device 400. The feed driver 430 supplies AC power to thefeeder element 440.

When AC power is supplied to the feeder element 440, AC current flows tothe feeder element 440. This produces an alternating magnetic field in adirection perpendicular to a power feed face 440 a. This alternatingmagnetic field excites the inductive current at the receiver element 510located near the feeder element 440, and causes power to be transmitted.

In the third and fourth embodiments, there are no particularrestrictions on the material and shape of the feeder element 440.However, a coil module can be used, for example. The coil module has ashape that spirals counter-clockwise toward the center of the spiral ina top view, for example.

The detector 450 inputs the output signal (e.g., the detection result)of the magnetic sensor 460 to the controller 420. The magnetic sensor460 detects the strength of the magnetic field generated from thereceiver element 510. Specifically, the magnetic sensor 460 detects thestrength of the magnetic field in the superposition direction of thereceiver element 510 and the feeder element 440 (see FIG. 28, discussedbelow). The magnetic sensor 460 is formed by a pickup coil, a magneticresistance element (MR element), a Hall element, a magnetic impedanceelement (MI element), or the like. The feeder device 400 in thisembodiment includes one or more magnetic sensors 460. The layout of themagnetic sensor 460 will be discussed in detail below.

The display component 470 displays a specific image or video.Information indicating the direction of the receiver device 500 (i.e.,the receiver element 510 of the receiver device 500) is displayed on thedisplay component 470, as discussed below.

As shown in FIG. 27, the receiver device 500 includes the receiverelement 510, a rectifier 520, a power supply component 530, a controller540, a rechargeable battery 550, and a memory component 560. Asdiscussed above, the receiver element 510 receives power transmittedfrom the feeder element 440. The AC power received by the receiverelement 510 is supplied to the rectifier 520. The rectifier 520 isformed by a diode, a capacitor, or the like. The rectifier 520 convertsthe AC power supplied from the receiver element 510 into DC power.

The power converted into DC by the rectifier 520 is supplied to thepower supply component 530. The controller 540 is a control means orprocessor for controlling the entire receiver device 500. The controller540 controls the conversion by the rectifier 520 of the AC powerreceived by the receiver element 510 into DC power. The controller 540also controls the storage of power by the power supply component 530 inthe rechargeable battery 550.

The memory component 560 is a memory means for storing various kinds ofinformation. The memory component 560 is formed by an EEPROM, forexample. The memory component 560 stores an identification number forthe feeder device 400.

Next, the layout of the magnetic sensor 460 in the feeder device 400will now be described through reference to FIGS. 28 and 29. FIG. 28 is aplan view of when the receiver element 510 and the feeder element 440are in a state of positional offset. FIG. 29 is an oblique view of whenthe receiver element 510 and the feeder element 440 are in a state ofpositional offset. FIG. 30 is a plan view of a first example of theinternal configuration of the feeder device 400. FIG. 31 is a lateralcross section along the XXXI-XXXI line in FIG. 30.

When power is fed between the receiver element 510 and the feederelement 440 by a non-contact method, the two must be moved relativelyclose together, such as about a few centimeters apart. Therefore, evenwhen the feeder element 440 is moved close to the receiver element 510,the feeder element 440 can sometimes be impossible to feed power to thereceiver element 510 if there is a large amount of positional offsetbetween the receiver element 510 and the feeder element 440.

The phrase “positional offset between the receiver element 510 and thefeeder element 440” refers to a state in which the receiver element 510is not within the region of the feeder element 440 when projected in thesuperposition direction of the receiver element 510 and the feederelement 440 (i.e., the direction perpendicular to the paper plane inFIG. 28) while the feeder device 400 is moved close to the receiverelement 510, as shown in FIG. 28. More precisely, as shown in FIG. 29,this phrase refers to a state in which the distance between the centeraxis of the feeder element 440 and the center axis of the receiverelement 510 is at least a specific distance L. In the illustratedembodiment, the specific distance L can be the communicable distance, orit can be any distance that is less than the communicable distance.

As shown in FIGS. 28 and 29, if the positional offset has occurred, thenpower will not be fed properly, such as a decrease in the power feedefficiency related to power feed from the feeder element 440 to thereceiver element 510. Therefore, in this embodiment, the controller 420determines the position and/or direction of the receiver element 510based on the output signal of the magnetic sensor 460 inputted from thedetector 450. Also, the controller 420 displays information indicatingthe position and/or direction of the receiver element 510 on the displaycomponent 470.

As discussed above, the magnetic sensor 460 detects the strength of themagnetic field generated from the receiver element 510. However, themagnetic sensor 460 also detects the strength of the magnetic fieldgenerated from the feeder element 440. The strength of the magneticfield generated from the receiver element 510 is weaker than thestrength of the magnetic field generated from the feeder element 440,particularly when the receiver element 510 is a passive tag. Thus, it isconceivable that the magnetic sensor 460 will detect mainly the strengthof the magnetic field generated from the feeder element 440.

In view of this, in this embodiment, the magnetic sensor 460 is disposedat a position where it is less likely that a signal indicating thestrength of the magnetic field generated from the feeder element 440will be included in the output signal of the magnetic sensor 460. Inthis embodiment, as shown in FIG. 30, the magnetic sensor 460 onlyincludes two magnetic sensors 460 a and 460 b (e.g., two magnetic sensorelements). These magnetic sensors 460 a and 460 b are made of magneticresistance elements.

As shown in FIG. 31, the magnetic field generated from the feederelement 440 has a first region R1 and a second region R2 with mutuallyopposite orientations or directions of the magnetic flux. The magneticsensors 460 a and 460 b are respectively disposed at positions thatallow the detections of the strength of the magnetic field in part ofthe first region and the strength of the magnetic field in the secondregion, out of the magnetic field generated from the feeder element 440.This will now be described in detail through reference to FIGS. 30 and31. In the following description, the fact that the magnetic sensors 460a and 460 b detect the strength of the magnetic field in part of thefirst region and in part of the second region, respectively, will alsobe stated simply as “detects the strength of the magnetic field in thefirst region and the second region.” In the illustrated embodiment, asshown in FIG. 31, the first region R1 is located outside the feederelement 440, while the second region R2 is located inside the feederelement 440.

As shown in FIG. 30, the magnetic sensors 460 a and 460 b arerespectively disposed at a position where the strength of the magneticfield in part of the first region outside of the feeder element 440 isdetected, and a position where the strength of the magnetic field inpart of the second region inside of the feeder element 440 is detected.The detector 450 obtains a magnetic field strength by adding thestrength of the magnetic field of the feeder element 440 detected by themagnetic sensor 460 a to the strength of the magnetic field of thefeeder element 440 detected by the magnetic sensor 460 b. The detector450 outputs the magnetic field strength to the controller 420 as thestrength of the magnetic field of the feeder element 440 detected by themagnetic sensor 460.

As shown in FIG. 31, if the magnetic sensors 460 a and 460 b arerespectively disposed in the first region and the second region,respectively, with the feeder element 440 in between. Thus, theorientation of the magnetic flux detected by the magnetic sensor 460 awill be substantially the opposite of the orientation of the magneticflux detected by the magnetic sensor 460 b. Therefore, if the absolutevalues of the strength of the magnetic field of the feeder element 440detected by the magnetic sensors 460 a and 460 b are substantially thesame, then the strength of the magnetic field of the feeder element 440detected by the magnetic sensor 460 as calculated by adding together thetwo output signals of the magnetic sensors 460 a and 460 b becomessubstantially zero. Thus, it will be less likely that a signalindicating the strength of the magnetic field of the feeder element 440is included in the output signal of the magnetic sensor 460.Accordingly, the magnetic sensor 460 will function mainly as a sensorfor detecting the strength of the magnetic field of the receiver element510 while the receiver element 510 and the feeder element 440 are movedclose together. In other words, in the output signals of the magneticsensors 460 a and 460 b, the signal components indicative of thestrength of the magnetic field of the feeder element 440 are cancelledout with respect to each other, while the signal components indicativeof the strength of the magnetic field of the receiver element 510 can besolely detected.

The processing executed by the controller 420 of the feeder device 400will now be described. FIG. 32 is a flowchart of an example of theprocessing executed by the controller 420 of the feeder device 400 inthis embodiment.

The controller 420 starts the processing for performing a display thatindicates the position and/or direction of the receiver element 510 whencommunication commences between the receiver element 510 and the feederelement 440. In step S11, the controller 420 acquires the output signalof the magnetic sensor 460 from the detector 450. As discussed above, itis less likely that a signal indicating the strength of the magneticfield of the feeder element 440 is included in the output signal of themagnetic sensor 460. Thus, the output signal of the magnetic sensor 460mainly includes a signal indicating the strength of the magnetic fieldof the receiver element 510.

In step S12, the controller 420 determines the positional relationbetween the receiver element 510 and the feeder element 440. As shown inFIG. 30, in the illustrated embodiment, the feeder device 400 includes asingle magnetic sensor 460 (i.e., a single pair of the magnetic sensors460 a and 460 b). In this case, the output signal of the magnetic sensor460 is compared to a specific threshold to determine how near or far thefeeder element 440 is to or from the receiver element 510.

On the other hand, as shown in FIG. 33, if the feeder device 400includes two magnetic sensors 460 (e.g., magnetic sensors 461 and 462),then the output signals of one magnetic sensor 460 (e.g., the magneticsensor 461) and the other magnetic sensor 460 (e.g., the magnetic sensor462) are compared to determine the one-dimensional direction of thereceiver element 510. Specifically, in this embodiment, the feederelement 440 is disposed in an area in the lower middle part of thefeeder device 400. Thus, there is rarely positional offset in the up anddown direction (the Y direction in FIG. 28), while there is oftenpositional offset in the left and right direction (the X direction inFIG. 28). In view of this, as shown in FIG. 33, the magnetic sensors 460are disposed on two sides of the feeder element 440 extending in the upand down direction.

With this configuration, if the strength of the magnetic field is higherwith the output signal of the magnetic sensor 462 than with the outputsignal of the magnetic sensor 461, for example, then it is determinedthat the receiver element 510 is present in the direction towards themagnetic sensor 462 with respect to the center point O of the feederelement 440 as the center. The layout of the two magnetic sensors 460can be varied according to the position of the feeder element 440 in thefeeder device 400. For example, when the feeder element 440 is disposedin an area in the left middle part of the feeder device 400, it isbelieved that positional offset will frequently occur in the up and downdirection. In view of this, the magnetic sensors 460 can be disposed ontwo sides of the feeder element 440 extending in the left and rightdirection.

Furthermore, as shown in FIG. 34, if the feeder device 400 includesthree magnetic sensors 460 (e.g., magnetic sensors 463, 464, and 465),or more than three magnetic sensors 460, then the two-dimensionaldirections of the receiver element 510 are determined by comparing theoutput signals of the various magnetic sensors 460.

As shown in FIG. 34, in the illustrated embodiment, a total of threemagnetic sensors 460 are disposed on two sides (two straight parts) ofthe feeder element 440 extending in the left and right direction. Onemagnetic sensor 460 (e.g., the magnetic sensor 463) is disposed on oneside, while two magnetic sensors 460 (e.g., the magnetic sensors 464 and465) on the other side. Positional offset in the up and down directionwith respect to the receiver element 510 is determined by comparing theoutput signal of the magnetic sensor 463 with the output signal of themagnetic sensors 464 and/or 465. Also, positional offset of the feederelement 440 in the left and right direction with respect to the receiverelement 510 is determined by comparing the output signals of themagnetic sensor 464 and the magnetic sensor 465.

The controller 420 determines positional offset in two-dimensionaldirections based on the positional offset in the up and down directionand in the left and right direction thus determined. There are noparticular restrictions on the number of magnetic sensors 460. However,the position and/or direction of the receiver element 510 can bedetermined more accurately by disposing more magnetic sensors 460. Forexample, as shown in FIG. 35, the positional offset in the up and downdirection or in the left and right direction with respect to thereceiver element 510 can be determined for each side by disposing twomagnetic sensors 460 on each side of the feeder element 440.

In step S13, the controller 420 displays the position and/or directionof the receiver element 510 on the display component 470 based on thepositional relation between the receiver element 510 and the feederelement 440 determined in step S12. For example, if the layout of themagnetic sensor 460 is as shown in FIG. 30, then a display indicatinghow near or far the feeder element 440 is to or from the receiverelement 510 is given as shown in FIG. 36. If the layout of the magneticsensors 460 is as shown in FIG. 33, then a display indicating theone-dimensional direction of the receiver element 510 with respect tothe center point O of the feeder element 440 as a reference is given asshown in FIG. 37. If the layout of the magnetic sensors 460 is as shownin FIGS. 34 and 35, then a display indicating the two-dimensionaldirections of the receiver element 510 with respect to the center pointO of the feeder element 440 as a reference is given as shown in FIG. 38.

In the layout of the magnetic sensor 460 shown in FIG. 30, when thedifference between the output signal of the magnetic sensor 460 and thespecific threshold is at or below a specific value, no positional offsethas occurred between the receiver element 510 and the feeder element440, or if it has occurred, it is so minor that it can be ignored. Also,when the difference between the output signals of the magnetic sensors460 in the layout of the magnetic sensors 460 shown in FIGS. 33 to 35 isat or below a specific value, no positional offset has occurred betweenthe receiver element 510 and the feeder element 440, or if it hasoccurred, it is so minor that it can be ignored. In this case, thecontroller 420 does not need to display anything on the displaycomponent 470, or can give a display indicating that no positionaloffset has occurred, as shown in FIG. 39, for example.

In step S14, the controller 420 determines whether or not power feed tothe receiver element 510 has ended. If power feed has not ended (No instep S14), then the flow returns to step S11. With this configuration,if the feeder device 400 is moved, then the display indicating theposition and/or direction of the receiver element 510 is updated. Ifpower feed has ended (Yes in step S 14), then the processing isconcluded.

Alternatively or additionally, when power feed to the receiver element510 has not yet ended, it can be determined in step S13 whether or not aspecific length of time has elapsed since the display indicating theposition and/or direction of the receiver element 510 was given. If thislength of time has elapsed, the flow returns to step S13. With thisconfiguration, the display is refreshed at regular time intervals.

In the illustrated embodiment, the feeder device includes the magneticsensor (e.g., the sensor), the feeder element, and the controller (e.g.,the notification component or notification means). The magnetic sensordetects the strength of a magnetic field (e.g., the magnetic fieldstrength). The feeder element generate a magnetic field. The feederelement performs the non-contact transmission of electrical power (e.g.,the non-contact electrical power transmission) to the receiver elementof the receiver device. The controller makes a notification related tothe positional offset between the feeder element and the receiverelement based on output signal from the magnetic sensor. In other words,the controller notifies the positional offset between the feeder elementand the receiver element based on the output signal indicative of themagnetic field strength.

The magnetic sensor is disposed at a position where it is less likelythat a signal indicating the strength of the magnetic field generatedfrom the feeder element when current flows to the feeder element will beincluded in the output signal of the magnetic sensor. In other words,the magnetic sensor is arranged with respect to the feeder element suchthat an effect of the magnetic field generated by the feeder element onthe output signal is suppressed.

Thus, the output signal of the magnetic sensor mainly includes a signalindicating the strength of the magnetic field generated from thereceiver element. The feeder device transmits power in a non-contactmanner to the receiver device, and the receiver element receives thetransmission of power from the feeder element. The position and/ordirection of the receiver element can then be accurately detected basedon the output signal of the magnetic sensor. The notification can begiven related to the positional offset between the feeder element andthe receiver element.

In the illustrated embodiment, the magnetic field generated from thefeeder element has a first region and a second region with mutuallyopposite orientations of the magnetic flux. The magnetic sensor isdisposed at a position where the strength of the magnetic field of thefirst region and the strength of the magnetic field of the second regioncan be detected. In other words, the magnetic sensor is arranged withrespect to the feeder element such that the magnetic sensor isconfigured to detect the magnetic field strength in first and secondregions, respectively. The magnetic field generated by the feederelement has mutually opposite magnetic flux orientations in the firstand second regions, respectively.

In the illustrated embodiment, the detected strength of the magneticfield of the first region and the strength of the magnetic field of thesecond region are added together. This makes it less likely that asignal indicating the strength of the magnetic field generated from thefeeder element will be included in the output signal of the magneticsensor. In other words, the magnetic sensor is arranged with respect tothe feeder element such that the magnetic field strength detected in thefirst and second regions cancels out with respect to each other. Thus,the position and/or direction of the receiver element can be detectedmore accurately.

In the illustrated embodiment, the controller calculates the one- ortwo-dimensional positional offset direction of the receiver element withrespect to the feeder element, and gives the notification of thedirection of the receiver element. In other words, the controllercalculates either one-dimensional or two-dimensional positional offsetdirection of the receiver element with respect to the feeder elementbased on the output signal. The controller notifies the positionaloffset direction of the receiver element. Thus, the user can transmitpower to the receiver element more efficiently by moving the feederdevice based on this notification.

In the illustrated embodiment, the controller gives a notificationindicating that there is no positional offset when the positional offsetbetween the receiver element and the feeder element is below a specificthreshold based on the output signal of the magnetic sensor. In otherwords, the controller notifies that there is no positional offset whilethe positional offset between the receiver element and the feederelement is below a specific threshold based on the output signal. Thus,the user can efficiently transmit power to the receiver element bymaintaining the current position of the feeder device.

Fourth Embodiment

Referring now to FIGS. 40 to 49, a non-contact power feed system inaccordance with a fourth embodiment will now be explained. In view ofthe similarity between the third and fourth embodiments, the parts ofthe fourth embodiment that are functionally identical to the parts ofthe third embodiment will be given the same reference numerals as theparts of the third embodiment. Moreover, the descriptions of the partsof the fourth embodiment that are identical to the parts of the thirdembodiment may be omitted for the sake of brevity.

In the third embodiment, a magnetic resistance element is used as themagnetic sensor 460. In the fourth embodiment, a less expensive pickupcoil is used as the magnetic sensor 460. This pickup coil include acircular pickup coil (or loop coil), and a figure-eight pickup coil.

FIG. 40 is a plan view of a second example of the internal configurationof the feeder device 400. FIG. 41 is a lateral cross section alongXLI-XLI line in FIG. 40. FIG. 42 is a plan view of a third example ofthe internal configuration of the feeder device 400. FIG. 43 is alateral cross section along XLIII-XLIII line in FIG. 42. In theillustrated embodiment, as shown in FIGS. 40 and 41, the feeder device400 includes a circular pickup coil as the magnetic sensor 460.Alternatively, as shown in FIGS. 42 and 43, the feeder device 400includes a figure-eight pickup coil as the magnetic sensor 460. Themagnetic sensor 460 is also called the pickup coil 460 below.

As shown in FIGS. 40 and 41, as viewed in a direction perpendicular tothe paper plane in FIG. 40, the magnetic field generated from the feederelement 440 is separated into a magnetic field generated in the firstregion outside of the feeder element 440 (e.g., a first magnetic field)and a magnetic field generated in the second region inside of the feederelement 440 (e.g., a second magnetic field). The orientations of themagnetic flux of these magnetic fields are mutually opposite, as shownin FIG. 41. The circular pickup coil 460 includes first and secondsensor components 466 and 467. The first sensor component 466 detectsthe strength of the magnetic field of part of the first region, whilethe second sensor component 467 detects the magnetic field of part ofthe second region. The detector 450 obtains the strength of the magneticfield by adding together the strength of the magnetic field of thefeeder element 440 detected by the first sensor component 466 and thestrength of the magnetic field of the feeder element 440 detected by thesecond sensor component 467. The detector 450 further outputs theobtained strength of the magnetic field to the controller 420 as thestrength of the magnetic field of the feeder element 440 detected by thepickup coil 460.

As shown in FIG. 40, the first sensor component 466 and the secondsensor component 467 are disposed so as to detect the strength of themagnetic field of part of the first region and part of the secondregion, respective. Furthermore, as shown in FIG. 41, the orientation ofthe magnetic flux detected by the first sensor component 466 and theorientation of the magnetic flux detected by the second sensor component467 are substantially opposite directions. Therefore, if the absolutevalues of the strength of the magnetic field of the feeder element 440detected by the first sensor component 466 and the second sensorcomponent 467 are substantially the same, then the strength of themagnetic field of the feeder element 440 detected by the pickup coil 460as calculated by adding together the two output signals will besubstantially zero. That is, it will be less likely that a signalindicating the strength of the magnetic field of the feeder element 440will be included in the output signal of the pickup coil 460. Thus, thepickup coil 460 will function mainly as a sensor for detecting thestrength of the magnetic field of the receiver element 510 when thereceiver element 510 and the feeder element 440 are moved closetogether.

Similarly, as shown in FIGS. 42 and 43, the figure-eight-shaped pickupcoil 460 includes a first coil 468 and a second coil 469. The first coil468 and the second coil 469 are respectively disposed at a positionwhere the strength of part of the magnetic field outside of the feederelement 440 (e.g., the first region) is detected, and a position wherethe strength of part of the magnetic field inside of the feeder element440 (e.g., the second region) is detected. The detector 450 obtains thestrength of the magnetic field by adding together the strength of themagnetic field of the feeder element 440 detected by the first coil 468and the strength of the magnetic field of the feeder element 440detected by the second coil 469. The detector 450 outputs the strengthof the magnetic field to the controller 420 as the strength of themagnetic field of the feeder element 440 detected by the pickup coil460.

As shown in FIG. 43, the first coil 468 and the second coil 469 aredisposed so as to detect the strength of the magnetic field in the firstregion and the second region, respectively. The orientation of themagnetic flux detected by the first coil 468 and the orientation of themagnetic flux detected by the second coil 469 are substantially oppositedirections. Therefore, if the absolute values of the strength of themagnetic field of the feeder element 440 detected by the first coil 468and the second coil 469 are substantially the same, then the strength ofthe magnetic field of the feeder element 440 detected by the pickup coil460 as calculated by adding together the two output signals will besubstantially zero. That is, it will be less likely that a signalindicating the strength of the magnetic field of the feeder element 440will be included in the output signal of the pickup coil 460. Thus, thepickup coil 460 will function mainly as a sensor for detecting thestrength of the magnetic field of the receiver element 510 when thereceiver element 510 and the feeder element 440 are moved closetogether.

This embodiment provides the same effect as the third embodiment. Inaddition, an inexpensive pickup coil is used as the magnetic sensor.Thus, the cost of the RF reader can be decreased.

In the above-mentioned third and fourth embodiments, the controller 420gives a display on the display component 470 indicating the positionand/or direction of the receiver element 510 to notify the user aboutthe position and/or direction of the receiver element 510. In otherwords, the controller 420 is an example of the notification component(or notification means) of the present invention. However, the positionand/or direction of the receiver element 510 can instead be conveyed tothe user by some method other than a display. For instance, the positionand/or direction of the receiver element 510 can be conveyed by soundemitted from a speaker. Specifically, as long as the position and/ordirection of the receiver element 510 can be recognized, anynotification method can be employed.

In the third and fourth embodiments, when the feeder device 400 includestwo magnetic sensors 460, the one-dimensional direction of the receiverelement 510 is determined. However, two-dimensional directions can bedetermined when the feeder device 400 further has an acceleration sensorthat detects the movement direction of the feeder device 400.

This will be described in detail through reference to FIG. 44. FIG. 44is a diagram illustrating a modification example of the feeder device400. The feeder device 400 has pickup coils 460 c and 460 d as magneticsensors 460. With this configuration, if the strength of the magneticfield of the output signal of the pickup coil 460 d is higher than thatof the output signal of the pickup coil 460 c, then it is determinedthat the receiver element 510 is present in the direction towards thepickup coil 460 d (right direction) with respect to the center point Oof the feeder element 440 as a reference. In addition, fluctuation inthe strength of the magnetic field detected by the pickup coils 460 cand 460 d can also be utilized. For example, if the strength of themagnetic field detected by the pickup coils 460 c and 460 d weakenswhile the feeder device 400 is moved in the direction of the arrow D3,then it can be determined that the receiver element 510 is present inthe upward direction. That is, the receiver element 510 is determined tobe present in the right direction and the upward direction (that is, theupper-right direction) from the feeder device 400.

Meanwhile, if the strength of the magnetic field detected by the pickupcoils 460 c and 460 d weakens while the feeder device 400 is moved inthe direction of the arrow D4, then it can be determined that thereceiver element 510 is present in the downward direction. That is, thereceiver element 510 is determined to be present in the right directionand the downward direction (that is, the lower-right direction) from thefeeder device 400.

In the third and fourth embodiments, the output signal of one magneticsensor 460 is compared with a threshold, or the output signals of two ormore magnetic sensors 460 are compared with respect to each other. Then,the one-dimensional direction or two-dimensional directions of thereceiver element 510 are indicated. However, alternatively, the centroidcoordinates P of the magnetic field generated from the receiver element510 can be calculated, and the direction of the centroid coordinates Prelative to the center point O of the feeder element 440 as a referencecan be determined as the direction of the receiver element 510.

When the positional coordinates of a j-th magnetic sensor 460 are(X_(j), Y_(j)), and the output signal of the magnetic sensor 460 is Hj(A/m), then the centroid coordinates P (X, Y) of the magnetic fieldgenerated from the receiver element 510 satisfy the following equations(3) and (4).

Σ(X _(j) −X)Hj=0  (3)

Σ(Y _(j) −Y)Hj=0  (4)

In the third and fourth embodiments, a loop antenna wound in a flatspiral is used as the feeder element 440. However, this is not the onlyoption. For example, a loop antenna with a three-dimensional spiralshape can be used as shown in FIGS. 45 and 46. In other words, in thisexample, the spiral shape extends in an axial direction of the feederelement 440. FIGS. 45 and 46 are modification examples of the feederelements 440 shown in FIGS. 30 and 31, respectively. However, this loopantenna can be applied to the feeder element 440 in other embodiments.

Here, the strength of the magnetic field of the feeder element 440generated in the first region, and the strength of the magnetic field ofthe feeder element 440 generated in the second region will be furtherdescribed. In the above embodiments, the strength of the magnetic fieldgenerated in the second region of the spiral feeder element 440 isaffected by the magnetic field generated from all parts (the four sides)of the feeder element 440, while the strength of the magnetic fieldgenerated in the first region is mainly affected by the magnetic fieldgenerated from just one part (one side) of the feeder element 440.Therefore, the strength of the magnetic field in the second region isgenerally higher than the strength of the magnetic field in the firstregion.

As shown in FIGS. 47 and 48, when the magnetic sensors 460 are pickupcoils, the sensors that detect the strength of the magnetic field in thesecond region of the magnetic sensors 460 (the second sensor component467 and the second coil 469) can be made smaller than the sensors thatdetect the strength of the magnetic field in the first region (the firstsensor component 466 and the first coil 468). This makes the sum of thestrength of the magnetic field of the feeder element 440 detected by themagnetic sensor 460 substantially zero.

Also, when the magnetic sensor 460 is a magnetic resistance element asshown in FIGS. 30 and 31, the position at which the magnetic sensor 460a detects the strength of the magnetic field in the first region can beset closer than the position at which magnetic sensor 460 b detects thestrength of the magnetic field in the second region with respect to thepart of the feeder element 440 that generates the magnetic fielddetected by the magnetic sensors 460 a and 460 b, as shown in FIG. 49.

That is, when the strength of the magnetic field of the first region andthe strength of the magnetic field of the second region are different,the magnetic sensor 460 is disposed such that the detection of thestrength of the magnetic field in the region with the stronger magneticfield will be suppressed more than detection of the strength of themagnetic field in the region with the weaker magnetic field. In otherwords, the magnetic field generated by the feeder element has a largerstrength in the second region than in the first region. The magneticsensor is arranged with respect to the feeder element such thatdetection of the magnetic field strength in the second region issuppressed more than detection of the magnetic field strength in thefirst region.

Also, alternatively, the strength of the magnetic field of the feederelement 440 detected by the magnetic sensor 460 can be set tosubstantially zero by adjusting the gain of the output signal of themagnetic field in the first region and/or the output signal of themagnetic field in the second region.

In the third and fourth embodiments above, while the power is fed to aportable electronic device such as a smart phone or a tablet terminal,the power can be fed to other than electronic devices. For example, thepower can be fed to a vehicle 600 equipped with a receiver element 610as shown in FIG. 50. In the illustrated embodiment, while a passengervehicle 600 is illustrated as an example in FIG. 50, this can instead bea motorcycle, a bicycle, a chair walker, or another such light vehicle.

As shown in FIG. 50, the receiver element 610 is disposed in theapproximate center of a hood 600 a of the vehicle or automobile 600. Thepower is supplied by moving the feeder device 400 close to the receiverelement 610. Here again, the position and/or direction of the receiverelement 610 is accurately detected based on the output signal of themagnetic sensor of the feeder device 400. The user is notified aboutpositional offset between the feeder element of the feeder device 400and the receiver element 610. The display component 470 displaysinformation about the positional offset as explained above.

In understanding the scope of the present invention, the term“comprising” and its derivatives, as used herein, are intended to beopen ended terms that specify the presence of the stated features,elements, components, groups, integers, and/or steps, but do not excludethe presence of other unstated features, elements, components, groups,integers and/or steps. The foregoing also applies to words havingsimilar meanings such as the terms, “including”, “having” and theirderivatives. Also, the terms “part,” “section,” “portion,” “member” or“element” when used in the singular can have the dual meaning of asingle part or a plurality of parts.

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. Furthermore, the foregoing descriptions of theembodiments according to the present invention are provided forillustration only, and not for the purpose of limiting the invention asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A communication device comprising: a sensorconfigured to detect magnetic field strength; an antenna configured togenerate a magnetic field, the antenna being further configured tocommunicate with a wireless device that is configured to generate amagnetic field during communication; and a notification componentconfigured to notify a positional offset between the antenna and thewireless device based on output signal indicative of the magnetic fieldstrength, the sensor being arranged with respect to the antenna suchthat an effect of the magnetic field generated by the antenna on theoutput signal is suppressed.
 2. The communication device according toclaim 1, wherein the sensor is arranged with respect to the antenna suchthat the sensor is configured to detect the magnetic field strength infirst and second regions, respectively, the magnetic field generated bythe antenna having mutually opposite magnetic flux orientations in thefirst and second regions, respectively.
 3. The communication deviceaccording to claim 2, wherein the sensor is arranged with respect to theantenna such that the magnetic field strength detected in the first andsecond regions cancels out with respect to each other.
 4. Thecommunication device according to claim 2, wherein the magnetic fieldgenerated by the antenna has a larger strength in the second region thanin the first region, and the sensor is arranged with respect to theantenna such that detection of the magnetic field strength in the secondregion is suppressed more than detection of the magnetic field strengthin the first region.
 5. The communication device according to claim 1,wherein the sensor includes a pickup coil.
 6. The communication deviceaccording to claim 1, wherein the notification component is furtherconfigured to calculate a positional offset direction of the wirelessdevice with respect to the antenna based on the output signal, thenotification component being further configured to notify the positionaloffset direction of the wireless device.
 7. The communication deviceaccording to claim 1, wherein the notification component is furtherconfigured to notify that there is no positional offset while thepositional offset between the wireless device and the antenna is below aspecific threshold based on the output signal.
 8. A feeder devicecomprising: a sensor configured to detect magnetic field strength; afeeder element configured to generate a magnetic field, the feederelement being further configured to perform a non-contact electricalpower transmission to a receiver element of a receiver device; and anotification component configured to notify a positional offset betweenthe feeder element and the receiver element based on output signalindicative of the magnetic field strength, the sensor being arrangedwith respect to the feeder element such that an effect of the magneticfield generated by the feeder element on the output signal issuppressed.
 9. The feeder device according to claim 8, wherein thesensor is arranged with respect to the feeder element such that thesensor is configured to detect the magnetic field strength in first andsecond regions, respectively, the magnetic field generated by the feederelement having mutually opposite magnetic flux orientations in the firstand second regions, respectively.
 10. The feeder device according toclaim 9, wherein the sensor is arranged with respect to the feederelement such that the magnetic field strength detected in the first andsecond regions cancels out with respect to each other.
 11. The feederdevice according to claim 9, wherein the magnetic field generated by thefeeder element has a larger strength in the second region than in thefirst region, and the sensor is arranged with respect to the feederelement such that detection of the magnetic field strength in the secondregion is suppressed more than detection of the magnetic field strengthin the first region.
 12. The feeder device according to claim 8, whereinthe sensor includes a pickup coil.
 13. The feeder device according toclaim 8, wherein the notification component is further configured tocalculate either one-dimensional or two-dimensional positional offsetdirection of the receiver element with respect to the feeder elementbased on the output signal, the notification component being furtherconfigured to notify the positional offset direction of the receiverelement.
 14. The feeder device according to claim 8, wherein thenotification component is further configured to notify that there is nopositional offset while the positional offset between the receiverelement and the feeder element is below a specific threshold based onthe output signal.